This invention relates to silicon substrate processing.
A microelectromechanical system (MEMS) typically has mechanical structures formed in a semiconductor substrate using conventional semiconductor processing techniques. A MEMS can include a single structure or multiple structures. MEMS have an electrical component, where an electrical signal activates each or is produced by actuation of each structure in the MEMS.
Various processing techniques are used to form MEMS. These processing techniques can include layer formation, such as deposition and bonding, and layer modification, such as laser ablation, punching and cutting. The techniques that are used are selected based on a desired pathway, recess and hole geometry to be formed in a body along with the material of the body.
One implementation of a MEMS includes a body having chambers formed therein and a piezoelectric actuator formed on an exterior surface of the body. The piezoelectric actuator includes a layer of piezoelectric material, such as a ceramic, and elements for transmitting a voltage, such as electrodes. The electrodes of the piezoelectric actuator can either apply a voltage across the piezoelectric material or transmit a voltage that is produced when the piezoelectric material is deformed.
One type of MEMS with piezoelectric actuators are micro-fluidic ejection devices. An actuator can include piezoelectric material that can be actuated by electrodes, causing the piezoelectric material to deform towards a chamber of the device. This deformed actuator pressurizes the chamber, causing fluid in the chamber to exit, for example, through a nozzle. The structure components, including the actuator, the chamber and the nozzle, can affect how much fluid is ejected. In a MEMS with multiple structures, forming uniformly sized components for each structure across the MEMS can improve the uniformity of performance of the MEMS, such as the uniformity of fluid quantities that are ejected. Forming uniform structures can be challenging when attempting to process each structure to have measurements that are within a few microns of other structures in the MEMS.